By means of electron gun evaporation Ge1-xSix:N thin films, in the entire range 0 <= x <= 1, were prepared on Si (100) and glass substrates. The initial vacuum reached was 6.6 x 10(-4) Pa, then a pressure of 2.7 x 10(-2) Pa of high purity N-2 was introduced into the chamber. The deposition time was 4 min. Crucible-substrate distance was 18 cm. X-ray diffraction patterns indicate that all the films were amorphous (a-Ge1-xSix:N). The nitrogen concentration was of the order of 1 at% for all the films. From optical absorption spectra data and by using the Tauc method the energy band gap (E-g) was calculated. The Raman spectra only reveal the presence of Si-Si, Ge-Ge, and Si-Ge bonds. Nevertheless, infrared spectra demonstrate the existence of Si-N and Ge-N bonds. The forbidden energy band gap (E-g) as a function of x in the entire range 0 <= x <= 1 shows two well defined regions: 0 <= x <= 0.67 and 0 <= x <= 67 due to two different behaviors of the band gap, where for x>0.67 exists an abruptly change of E-g(x). In this case E-g(x) versus x is different to the variation of E-g in a-Ge1-xSix and a-Ge1-xSix:H. This fact can be related to the formation of Ge3N4 and GeSi2N4 when x <= 0.67, and to the formation of Si3N4 and GeSi2N4 for 0.67 <= x (C) 2012 Elsevier B.V. All rights reserved.